Sheldon Kenton, senior vice president of global employer sales at Cigna, said: "Greater recognition of the challenges of being on assignment in the United States is vital. Navigating a complex health system as well as developing an understanding of the financial and tax consequences of working in the US, all present considerable challenges to US-bound expats.

"My personal experience as an expat has further driven home the crucial need for better preparation, guidance and support."

America is the second most popular country for British expats to relocate to behind Australia, with close to one million Britons. Another hurdle for new arrivals to navigate is sales tax, which is added at the point of sale rather than included on the price tag – prompting some mental arithmetic while shopping.

Neil Greenwood, a British lawyer working in New York, said: "I always knew there was a lot of red tape involved in moving to America but never this much. Thankfully it was worth it though as this is probably the most exciting city in the world."

Comparing the 2001 Cigna/NFTC survey to this year’s highlights that today’s expats are older, on shorter assignments and almost three times more likely to leave their spouse and family at home.

A total of eight per cent of expats were travelling without their spouse or partner 12 years ago, compared with 23 per cent in 2013.

There has also been a notable shift in the location of expat assignments from the West to the East. In 2001, five per cent of expats surveyed were living in Asia while 43 per cent were based in Europe. But for 2013, Asian-based expats have risen to 13 per cent while European ones have slipped to 22 per cent.